如何使用 MySQLdb 创建外键

Question

导入 MySQLdb 模块后，我继续连接到 MySQl Maria db:

import  MySQLdb
db = MySQLdb.connect(host="localhost", user="user", passwd="pass", db="test")

现在我想创建两个表：Writers 和 Readers。我希望 Readers 有一个指向相应 Writer:

的外键属性 "Writer_id"

with db:
    cHandler=db.cursor()
    cHandler.execute( "CREATE TABLE Writers(Id INT PRIMARY KEY AUTO_INCREMENT)")
    cHandler.execute( "CREATE TABLE Readers(Id INT PRIMARY KEY AUTO_INCREMENT, FOREIGN KEY(Writer_id) REFERENCES Writers(Id) ) ")

但是代码失败并出现错误：

_mysql_exceptions.OperationalError: (1072, "Key column 'x' doesn't exist in table")

哪里出错了？

Answer 1

您必须先在 Readers table 中创建 writer_id，然后再将其设置为外键。

cHandler.execute( "CREATE TABLE Readers(Id INT PRIMARY KEY AUTO_INCREMENT, Writer_id INT ) ")
cHandler.execute( "alter table Readers
add foreign key (Writer_id)
references Writers(Id)")

Answer 2

with db:
    cHandler=db.cursor()

    cHandler.execute("DROP TABLE IF EXISTS Writers")
    cHandler.execute("DROP TABLE IF EXISTS Readers")

    cHandler.execute("CREATE TABLE Writers(Id INT PRIMARY KEY AUTO_INCREMENT, name TEXT)")
    cHandler.execute("CREATE TABLE Readers(Id INT PRIMARY KEY AUTO_INCREMENT, name TEXT, Writer_id INTEGER, FOREIGN KEY(Writer_id) REFERENCES Writers(Id))")

如何使用 MySQLdb 创建外键

How to create Foreign Key using MySQLdb

python

mysql

mysql-python